Theoretically, the USB 3.1 Type-C devices supporting the USB power delivery mode allow data rates up to 10 GB/s and up to 100 W of power to be delivered with a maximum voltage of 20 V and a maximum current of 5 A. The power to be delivered between two USB 3.1 devices Type-C is negotiable via specific controllers and the electrical power supply may advantageously be bidirectional between various USB 3.1 Type-C devices.
Generally speaking, a USB Type-C cable is designed so as to be coupled and to establish a power supply and communications line between a USB Type-C device referred to as “source” and a USB Type-C device referred to as “receiver.”
The connectors of the USB 3.1 Type-C source or receiver devices each comprise two symmetrically-disposed channel configuration pins in such a manner as to render the connectors reversible. The two channel configuration pins of the source device are connected to ‘pull-up’ resistors or to current sources, whereas the two channel configuration pins of the receiver device are connected to ‘pull-down’ resistors.
In general, the high electrical current of 5 A present in the USB Type-C cables introduces large voltage drops and it is indispensable to avoid total voltage drops greater than 750 mV when the power supply voltage of the USB Type-C cables is, for example, 5 V since, in that case, a USB Type-C source device risks not being recognized by a connected USB Type-C receiver device.
By way of example, a source device cannot be recognized as a “source” by a receiver device when the power supply voltage output from the source device is too low because of the large voltage drop in a USB Type-C cable coupled between the source device and the receiver device.
Furthermore, the poor qualities and/or the non-conformities of the USB 3.1 Type-C cables may also increase the voltage drops within the cables.